Arsenal and Liverpool have failed their star players, according to a renowned football scout

Alexis Sánchez is linked with a £70 million move to Manchester City. Clive Mason / Getty When players decide they want to leave, it doesn't happen overnight; it's the result of bad management and it's a situation clubs should never allow to develop, writes football scout and former England international Trevor Steven.

You can't blame the players. They want to be reassured that their team is capable of winning now and heading in the right direction, and that means clubs being brave in the transfer market.

The days of John Terry and Steven Gerrard staying at the same club for their whole career are gone. The money available is astronomical now and the wages can differ between clubs hugely; players have short careers and people have to understand that.

Ultimately, however, the best players want to go where they feel they can not only get a good financial deal for themselves but also where they can win titles.

In the case of Alexis Sánchez, Arsenal have failed to support him by signing more players of the same calibre. He stands out for his quality and his will to win and the Gunners sorely need more like him.

Sánchez's situation is also a legacy of last season, when more bad management allowed uncertainty over Arsene Wenger's future to drag on and that indecision contributed to Arsenal missing out on qualification for the Champions League.

Barcelona has tested Liverpool's resolve with multiple offers for Philippe Coutinho. Michael Regan / Getty Images Liverpool have also faced unrest from Philippe Coutinho, amid interest from Barcelona, although they have the advantage of being in Europe's top club competition.

Yet they too seem to have failed to convince Coutinho that he is at the right place. They haven't been bold in their transfer business and signing Naby Keita for next summer, even in a club record deal, isn't going to do it.

When key players want to leave it is bound to affect the rest of the squad. It is destabilising and the constant transfer speculation can generate anxiety.

Clubs can refuse to sell but players have so much power now that it can be difficult. If they refuse to listen to offers then it can get messy and players can down tools.

This is a critical moment for Sanchez, who is wanted by Manchester City. The Chilean turns 29 in a few months' time, so this is his one last shot at a four-year contract.

It's also easy to see the appeal of City, Manchester United or Chelsea when the atmosphere at Arsenal appears to have been tainted and the mood destroyed following Sunday's 4-0 defeat at Liverpool.

Arsenal are in a terribly worrying situation so early in the season and, with the way they're playing, the negativity around Wenger and just 48 hours of the transfer window left, there is no great outcome for them, but they might as well sell.

A part-exchange with City involving Raheem Sterling wouldn't placate supporters, who I don't think would see him as a significant upgrade on Theo Walcott.

A mooted deal involving Sergio Aguero would save face and be the best result for Arsenal, although if City are serious about the Champions League this season I cannot see Pep Guardiola letting him go.